1. Field of the Invention
The present invention relates generally to rotors for automotive hydraulic brake systems and, more particularly, to an improved rotor for an automotive hydraulic brake system, wherein the improved rotor houses a compressed coolant that reduces heat build-up and minimizes warping and deterioration of the rotor and associated brake pads.
2. Description of the Related Art
As is well-known in the art, hydraulic brakes for automobiles and other vehicles typically operate calipers which press at least one associated brake pad against at least one exposed plate of a rotor mounted to rotate with a rotating axle of the automobile. The rotation of a rotating rotor may be slowed by translating some of the kinetic energy of the rotating rotor to heat energy. Typically, this energy translation is accomplished by pressing the brake pad against the rotating rotor, thereby causing friction wherein the kinetic energy of the rotating rotor is translated to heat energy, thereby slowing the rotation of the rotor and therefore, the axle. Much of the generated heat energy is conducted directly to the rotor, which is typically constructed of a metal material and therefore an excellent heat conductor. Heat build-up on rotors is a problem that causes warping and deterioration of the rotor and the associated brake pads. Further, a brake pad which presses against a hot rotor will wear down quicker than a brake pad pressing against a cooler rotor. As a result, an exposed brake shoe under a worn brake pad may cause rough service to the rotor.
Another problem occurs from heat transfer through the calipers of the hydraulic brakes used on automobiles, such as racecourse, that typically must brake from high speeds. Braking from high speeds requires either pressing the brake pad harder against the rotor or pressing the brake pad against the rotor for a longer period of time than for slower speeds. Therefore, braking from high speeds typically generates more heat energy than braking from slower speeds generates. When braking from the high speeds which are typically experienced by racecourse, the additional heat energy may transfer also to the calipers and to the brake fluid. As a result, overheating and potential boiling of brake fluid, which may result in loss of braking ability, is an ongoing problem which typically occurs when braking from high speeds.
Numerous attempts have been made to correct for the foregoing problems. As is well-known in the art, constructing the rotor of multiple plates that are spaced by a plurality of heat-dissipating metal fins, as shown in FIGS. 1 and 2, addresses the problem of excessive heat build-up on brake rotors. Typically, as shown in FIG. 2, the heat-dissipating fins extend from an inner circumference to an outer circumference of at least two rotor plates. A free flow of air is thereby permitted between the plates and the fins. Therefore, heat energy, which is generated while braking, that transfers to the rotating rotor and to the heat-dissipating fins, ultimately transfers to the free flow of air passing between the plates and the fins. However, heat transfer to the air is not efficient enough in a variety of braking situations that generate excessive heat energy that causes warping and deterioration of the rotor and the brake pads.
Furthermore, U.S. Pat. No. 4,736,821, issued in the name of Res, discloses a fluid cooled brake having a pump that draws lubricating fluid from a sump and delivers the fluid to circulate and then be removed from within a closed annular chamber. U.S. Pat. No. 4,014,410, issued in the name of Bryant, discloses a disc brake with a fluid cooled actuator, wherein a fluid circuit includes a direct line leading to the master cylinder, a by-pass line leading to the master cylinder and a line leading from the cylinders of one side to the cylinders of the other side. However, these references require a fluid circuit through which fluid is exchanged within or about the brake rotor, rather than remaining within the rotor, thereby increasing the expense to manufacture the brake system.
Consequently, a need has been felt for providing a rotor which overcomes the problem of reducing heat build-up on the rotor of an automotive hydraulic brake system, wherein warping and deterioration of the rotor and associated brake pads is minimized, and wherein overheating and potential boiling of brake fluid is minimized when braking from high speeds, by transferring heat energy from the rotor with a fluid coolant medium which remains contained within the rotor.